According to probability theory:

a. 58% of a sample falls within plus or minus one standard error of the population parameter.
b. 68% of a sample falls within plus or minus one standard error of the population parameter.
c. 75% of a sample falls within plus or minus one standard error of the population parameter
d. 50% of a sample falls within plus or minus one standard error of the population parameter.
e. 90% of a sample falls within plus or minus one standard error of the population parameter.